THE SOURCE OF MUSCULAR POWER, 819 



This, Professor Flint claims, sIioa^s that the work performed was ac- 

 complished at the expense of muscular tissue, which was destroyed and 

 caused the increase in the relative excretion. 



Were the data as to food more exact, this might be the case ; but, 

 as it is, the result seems to need further confirmation before it can be 

 accepted. 



The only other similar result, so far as we know, is one recently 

 obtained by E. von Wolff in experiments on the horse ; but, having 

 access only to a brief abstract, we are unable to judge of the accuracy 

 of the work, though from the high reputation of this investigator it is 

 to be assumed that it was executed with every precaution. It was 

 found that an increase of the work performed was accompanied by an 

 increased excretion of nitrogen in the urine ; but the author reserves 

 the details of his experiments till further observations shall have con- 

 firmed or disproved their results, and at present, until the subject has 

 been more thoroughly investigated, we must follow the preponderance 

 of evidence, which is most decidedly in favor of Voit's result, viz., 

 that work does not increase the destruction of proteine in the body 

 and the consequent excretion of nitrogen through the kidneys. 



Thus far we have simply been considering experimental results, 

 without regard to the conclusions to be drawn from them ; we now 

 come to their interpretation, and here it must be admitted, at the out- 

 set, that the data now at command are not sufficient to enable us to 

 solve the problem of the source of muscular power. But, though we 

 do not know precisely what the proximate source of muscular power 

 is, we are able to indicate with tolerable certainty the direction in 

 which an answer to this question is to be sought, and to say that cer- 

 tain conclusions have a high degree of probability. 



It would seem at first thought that if, during work, the oxidation 

 of non-nitrogenous matters in the body increases, while no more pro- 

 teine is destroyed than during rest, the non-nitrogenous matters must be 

 the source of the power exerted. This appears to be Professor Flint's 

 view, as indicated by several passages in his book ; but, though it may 

 be a probable conclusion, it is by no means a necessary one. We have 

 already mentioned the fact that Voit and his followers still consider 

 the constant decomposition of circulatory proteine which goes on in the 

 body to be the source of muscular power, comparing it to a constantly 

 flowing stream, the energy of which may be converted at will into mo- 

 tion, or be allowed to take the form of heat ; and there is nothing in 

 the experimental results above adduced to forbid this interpretation. 



It has been shown by Voit and Pettenkof er to be at least very prob- 

 able that proteine in its decomposition in the body takes up the elements 

 of water and splits up into urea and/ ; and it is easy to show by cal- 

 culation that 100 parts of proteine could produce in this way 51*4 parts 

 of fat. This process, now, takes place during rest, and it is quite con- 



